The younger sister of the allegedly murdered teenager Shafilea Ahmed told a court that it had been a relief after seven years to tell police that she witnessed her parents kill her.

Giving evidence on the fourth day of the trial at Chester crown court on Thursday, Alesha Ahmed, 23, said there was a delay in telling the police about what happened but she had finally "had enough". It was a relief, she said, to tell the police after seven years of being haunted by her 17-year-old sister's alleged murder.

When Alesha was at university she said she felt herself going down the same path as Shafilea with her parents and she thought she, too, would have to go to Pakistan and be married.

"I think I'd just had enough," she told the court. She said relations between her and her parents were "not as extreme" as they had been with Shafilea. But "I did feel myself going down the same path as Shafilea," she said.

"There was the pressure to go to Pakistan. It was just an awful lot of pressure. That is when I decided to speak out."

Her parents, Iftikhar and Farzana Ahmed, sat just feet away in the dock in the well of the wood-panelled courtroom as Alesha gave evidence from behind a screen.

They deny murdering their eldest daughter, Shafilea, at the family home in Warrington, Cheshire, in September 2003. Her badly decomposed remains were discovered beside a flooded Cumbrian river in February 2004. However, it was not until 2010 that Alesha provided the "final piece of the puzzle" about her death, the court has heard, when she was arrested for her role in a robbery at the house. She has pleaded guilty to the offence and will be sentenced at a later date.

The court heard that Alesha made the disclosure that she witnessed the murder to her solicitor and a police officer while she was in custody for the robbery.

Questioned by Andrew Edis QC, for the prosecution, about why she made the claim after all these years, she replied: "I think at that point I was really suffering with the family … the buildup to the robbery. It all got too much, and to be honest I think it was a relief more than anything to be able to tell someone finally."

Asked why she had kept quiet for all those years, she said: "I think it was not until I went to uni I saw how wrong family life was. When you get used to something, it becomes normal and that's when I saw it wasn't normal, really.

"I think what happened to my sister was wrong but because it's your parents you think it's normal because you still love them. I think at uni I did feel the way my sister had – you want to fit in with everyone else, but you are still being forced to live in a different way. I think that's what made me crack."

She said she was in a state of "emotional distress" when she made the witness statement about the murder and she had to let it out. When she was at university she lived like a western student and returned at weekends and holidays to her parents' home.

Alesha said her parents had set up a number of potential suitors but she refused to marry "someone she didn't know" and her relationship with her mother and father "completely broke down" as it meant either living the way they wanted her to live, or live on her own. "Both were a struggle", she explained to the jury.

When she arranged the robbery, she said she was not thinking properly. On 25 August 2010, three or four masked men burst into the house and searched for money, tying up everyone apart from Alesha.

She told the court she was arrested after her mother and brother told police the thieves had known her name.

"My mental state wasn't very good, being between the two cultures, trying to please everyone." She was behaving out of character and drinking at university. "I was not being myself any more."

The trial continues on Monday, when Alesha will be cross-examined by the defence.